The kinetic energy of a particle continuously increases with time. It follows that:
1. | its potential energy must decrease with time |
2. | the net force acting on it cannot be perpendicular to its path |
3. | the net force acting on it is along the velocity |
4. | friction cannot act on it |
Given below are two statements:
Assertion (A): | The net work done by gravity is equal to the loss in the vertical component of the kinetic energy for a projectile. |
Reason (R): | The work-energy theorem applies to all systems including projectiles. |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | (A) is False but (R) is True. |
A projectile is launched from a cliff of height \(h,\) with an initial speed \(u,\) at an angle \(\theta.\) The speed with which it hits the ground:
1. | \(u \text{sin}\theta\) | depends on the vertical component,
2. | \(u \text{cos}\theta\) | depends on the horizontal component,
3. | \(u,\) but not on \(\theta\) | depends on
4. | \(u \text{tan}\theta\) | depends on the quantity
When a fan is switched on and it begins to rotate:
1. | Its K.E. increases |
2. | Work is done by centrifugal force |
3. | Work is done by centripetal forces |
4. | Mechanical forces do not do any work |
A particle of mass '\(m\)' is released from the origin, and it moves under the action of a force: \(F(x)= F_0-kx\)
The maximum speed of the particle is, \(v= \)
1. | \(\sqrt{\dfrac{F_0^2}{mk}}\) | 2. | \(\sqrt{\dfrac{2F_0^2}{mk}}\) |
3. | \(\sqrt{\dfrac{F_0^2}{2mk}}\) | 4. | \(2\sqrt{\dfrac{F_0^2}{mk}}\) |